KABUL, Afghanistan – Three international troops died in insurgent attacks and a senior Afghan police official was assassinated, officials said Thursday as violence intensified.

NATO also said it captured a suspected Taliban-linked supplier of bomb-making materials overnight in an eastern province, as the international security force steps up operations in the south and east, boosted by thousands of new American troops sent to try to turn around the nearly 9-year-old war.

The force said a U.S. service member was killed by an insurgent attack in eastern Afghanistan on Thursday. Two other service members, whose nationalities were not released, died in separate roadside bomb attacks in the south. No other details were available.

So far this month, 22 international troops have died in Afghanistan.

Violence has been increasing across the country as the U.S. has poured in 30,000 more troops to try to reverse Taliban gains, improve security and build up the government of President Hamid Karzai.

On Wednesday evening, Mohammad Gul, the police intelligence director for western Kabul, was ambushed and killed by gunmen outside his home, said the city’s criminal investigations chief, Abdul Ghfar Sayed Zada.

In the eastern province of Khost, a combined Afghan-international force captured a suspected explosives supplier for the Haqqani network, a powerful militant group with links to both the Taliban and al-Qaida, NATO said in a statement.