US President Barack Obama has said the US is a "full partner" with Mexico in its fight against the drug cartels.

美国总统奥巴马称美国是墨西哥反毒品行业联盟之战的“完全的拍档”

High hopes for Obama visit

Speaking in Mexico City, he said the US must stem（堵住，阻止） the flow of guns across the border that is fuelling the bloodshed.

Following talks with his Mexican counterpart（相似之物）, Felipe Calderon, Mr Obama said he would push the US Senate to ratify¹（批准，认可） a small arms trafficking treaty（条约，协定）.

The two leaders also agreed on a new partnership² to fight climate change and promote green energy production.

Hours before Mr Obama arrived, 15 gunmen and one soldier were killed in a shoot-out in southern Mexico, officials said.

Mexico's defence department said soldiers on a drug patrol came under fire from gunmen in a vehicle in the remote, mountainous state of Guerrero.

Mr Obama again acknowledged America's shared responsibility for the violence which has killed more than 6,000 people over the last year.

'New era'

Speaking at his welcoming ceremony, Mr Obama said the US needed to do more to help.

"At a time when the Mexican government has so courageously³（勇敢地） taken on the drug cartels that have plagued（折磨，苦恼） both sides of the borders, it is absolutely critical that the United States joins as a full partner in dealing⁴ with this issue," Mr Obama said.

He said he preferred to focus on enforcing existing laws to keep US assault（袭击，突袭） weapons out of Mexico, rather than trying to renew a US ban which expired（到期） in 1994.

Backtracking on a campaign pledge to reinstate（恢复） the ban, Mr Obama said that doing so would be politically difficult.

The Mexican leader hailed（欢呼，致敬） a "new era" where Mexico and the US faced challenges together.

Aside from combating the drug menace（威胁，胁迫）, Mr Calderon said the two leaders had agreed on a new framework on clean energy and climate change that set out a legal framework and bilateral⁵（双边的） market mechanisms⁶ for carbon emissions⁷（散发，传播）.

He said proposals to reduce greenhouse gas emissions would also be discussed.

Regional summit

Mexico is Mr Obama's only stop on the way to the Summit of the Americas, being held in Trinidad and Tobago.

For most Mexicans, the main concern is reviving（返青） the economy, says the BBC's Stephen Gibbs in Mexico City.

Mexico sends 80% of its exports to the US and millions of Mexican families rely on remittances⁸（汇款） from relatives working north of the border, our correspondent says.

Relations between the US and Mexico hit a low point earlier this year when a US military report said drugs-related violence was in danger of turning Mexico into a failed state.

Over the past two years, some 8,000 people have been killed as gangs battle for control of the lucrative⁹（获利的，合算的） drug trafficking routes into the US.

But President Obama's administration has since expressed solidarity¹⁰ with Mr Calderon who has sent hundreds of troops to regain¹¹ control of the worst-affected areas.

During a visit to Mexico City in March, US Secretary of State Hillary Clinton said that the US shared responsibility for the drugs problem.

She said America's "insatiable（不知足的，贪得无厌的） demand" for illegal drugs fuelled the trade and that the US had an "inability" to stop weapons from being smuggled¹²（走私） south.

Mr Obama has sent hundreds of federal agents along with high-tech¹³ surveillance（监视，监督） equipment and drug-sniffer（嗅探者） dogs to help Mexico fight the cartels.

On Wednesday, the US placed three Mexican organisations（组织） on its list of suspected drug syndicates（企业联合，联合组织） and Mr Obama also charged a senior official with stopping drugs-related violence crossing from Mexico into the US.