KABUL, Afghanistan - An Afghan soldier killed one U.S. Marine and wounded another before being shot to death in return fire Sunday in southern Afghanistan, the latest in a series of attacks against foreigners blamed on government forces within their own ranks.

Nearly 20 such attacks this year have raised the level of mistrust between the U.S.-led coalition and their Afghan partners as NATO gears up to hand over security to local forces ahead of a 2014 deadline for the withdrawal of combat troops.

In another sign of deteriorating security, the United States is considering abandoning plans for a consulate in the country's north because the building chosen was deemed too dangerous to occupy. The United States spent $80 million on the project despite glaring security deficiencies in the former hotel, according to a copy of a document drafted by the U.S. Embassy in Kabul.

Those problems - including shoddy construction that would lead to a "catastrophic failure" of the building in a car bomb attack - were overlooked and waivers to strict State Department building rules were granted as officials rushed to open the consulate in Mazar-i-Sharif as a sign of America's long-term commitment to Afghanistan, the diplomatic memo shows.

While Mazar-i-Sharif was considered relatively safe when the project was approved in 2009, the memo said, a number of incidents in the city indicate that is no longer the case, including an attack last April on a nearby U.N. compound in which a mob stormed the facility and killed seven foreigners - three workers and their guards.

U.S. Embassy spokesman Gavin Sundwall declined to comment on the report, saying only that "the security situation has evolved in Afghanistan and any decisions we make are driven by our responsibility to ensure the safety of our personnel."

Also Sunday, a NATO service member was killed by a bomb in eastern Afghanistan, the alliance said, raising to 139 the number of foreign troops deaths so far this year.

The heads of the House and Senate intelligence committees claimed Sunday that the Taliban has actually grown stronger since 33,000 more U.S. troops were deployed to Afghanistan in 2010.

Sen. Dianne Feinstein, a Democrat, and Rep. Mike Rogers, a Republican, offered the pessimistic report on CNN's State of the Union after a fact-finding trip to the region where they met with President Hamid Karzai.

When asked if the Taliban's capabilities have been degraded, Feinstein said: "I think we'd both say that what we've found is that the Taliban is stronger."

More than 1,800 U.S. troops have been killed in the decade-long war. About 90,000 service members remain deployed, down from a peak of more than 100,000 last year.

Rogers said that he and Feinstein agree the first step should be for the U.S. to designate the Haqqani group a terrorist network and "take aggressive steps" to disrupt their operations. He said that group is responsible for nearly 500 U.S. deaths and continues to operate outposts along the Afghan-Pakistani border.