UNITED NATIONS - The United States, the world's largest arms dealer, has joined more than 90 other nations in signing a treaty that regulates global arms trading, but there is strong resistance in the Senate, which must ratify it.
Secretary of State John Kerry, who signed the Arms Trade Treaty on Wednesday, said it was a "significant step" in keeping the world safe and preventing terrorists and others from obtaining conventional weapons.
The Obama administration's move is seen as critical to the treaty's success. The U.S. was the 91st country to sign, but the treaty will not take effect until 50 nations have ratified it. Only four had ratified the treaty as of Wednesday.
Many of the world's other top arms exporters have yet to sign and opposition in the Senate, backed by the powerful National Rifle Association, means U.S. ratification will be difficult.
"This is about reducing the risks of international transfers of conventional arms that will be used to carry out the world's worst crimes," Kerry said.
He said it would require other countries to put in place the same arms export restrictions that the United States already has in force.
"This is about keeping Americans safe and keeping America strong, and this is about promoting international peace and global security," he said.
Addressing U.S. critics of the treaty, the former senator said fears that it would undermine Americans' constitutional right to keep and bear arms are not grounded in reality.
For one, the treaty does not regulate domestic weapons sales.
"This treaty will not diminish anyone's freedom," he said. "It recognizes the freedom of both individuals and states to obtain, possess, and use arms for legitimate purposes."
Kerry said the U.S. "would never think about supporting a treaty that is inconsistent with the rights of Americans, the rights of American citizens to be able to exercise their guaranteed rights under our Constitution."
Sen. Bob Corker of Tennessee, the top Republican on the Senate Foreign Relations Committee, is one of several conservative lawmakers who have concerns about the treaty, which he said raises "significant legislative and constitutional questions."
In a letter sent Tuesday to President Barack Obama, Corker warned the administration against taking any steps to put the treaty in place unless and until the Senate ratifies it.
"The Senate has not yet provided its advice and consent, and may not provide such consent," he wrote.
In addition to questions about the Second Amendment, Corker said many of the treaty's provisions regarding arms sales will require congressional approval.
The treaty will require countries that ratify it to establish national regulations to control the transfer of conventional arms and components and to regulate arms brokers. It will not control the domestic use of weapons in any country.
It prohibits the transfer of conventional weapons if they violate arms embargoes or if they promote acts of genocide, crimes against humanity or war crimes, and if they could be used in attacks on civilians or civilian buildings such as schools and hospitals.
The treaty covers battle tanks, armored combat vehicles, large-caliber artillery systems, combat aircraft, attack helicopters, warships, missiles and missile launchers, and small arms and light weapons.
In considering whether to authorize the export of arms, a country must evaluate whether the weapons would be used to violate international human rights laws or be employed by terrorists or organized crime elements. A country also must determine whether the weapons would contribute to or undermine peace and security.
In addition, the treaty requires countries to take measures to prevent the diversion of conventional weapons to the illicit market.
What impact the treaty will have in curbing the global arms trade - now estimated at between $60 billion and $85 billion annually - remains to be seen. Much will depend on which countries ratify it, and how stringently it is implemented once it comes into force.
U.N. chief Ban Ki-moon and numerous human rights and humanitarian groups hailed the U.S. move, saying it sent a powerful signal to countries that have yet to sign.
"It is of particular significance that the largest arms exporting country in the world, the United States, is now also among those countries who have committed themselves to a global regulation of the arms trade," Ban said in a statement.
Oxfam America called it "a significant victory for human rights and development." Human Rights First urged the Senate to put aside partisan politics to send a "a strong message to those countries committing mass atrocities, like the current Syrian regime, as well as those who are arming them, like Russia."
Frank Januzzi of Amnesty International USA said he hoped the signing would show that the Obama administration "is politically committed to ending the unscrupulous trade in deadly weapons used by dictators, war lords and criminal gangs to commit atrocities."