Kabul, Afghanistan (CNN) -- Four NATO service members were killed Saturday when a roadside bomb exploded in eastern Afghanistan, but this didn't stop U.S. Defense Secretary Robert Gates from touting security strides that could help coalition and Afghan forces turn "a corner" in the fight against militants.

"It seems to me that between the success we've already enjoyed and the increased capacity of the Afghan forces, we are in a position based on conditions on the ground as the president has said, to consider some modest drawdowns beginning in July," Gates said.

Gates, who is stepping down at the end of the month, paid his last visit to Afghanistan as secretary of defense. His trip comes on the same day as the deadly attack, claimed by the Taliban.

The outgoing secretary met with Afghan President Hamid Karzai and the two held a news conference. Gates was upbeat about progress despite an uptick in fighting between insurgents and soldiers.

"I believe that if we can hold on to the territory that has been recaptured from the Taliban between ourselves and the Afghan forces and perhaps expand that security, that we will be in a position toward the end of this year to perhaps have a successful opening with respect to reconciliation, or at least be in a position where we can say we've turned a corner here in Afghanistan," he said, referring to political reconciliation talks.

Karzai awarded Gates the Wazir Akbar Khan medal, the highest governmental award. It's named after an Afghan leader who fought against the Russians.

Gates commented on the period from the 1989 Soviet withdrawal to the Sept. 11, 2001 attack on the United States by al Qaeda -- the terror organization once harbored by the Taliban when it governed Afghanistan.

"Twenty years ago, the U.S. walked away from Afghanistan in the wake of the Soviet withdrawal, believing that our job was done, that what happened here subsequently would not affect our own security and national interests," Gates said, referring to American support of the Afghan mujahideen fighters who challenged the Soviets.

"I remember this all too well, as I was in a senior position in the U.S. government at the time. That tragic miscalculation was exposed by the attacks of September 11, 2001."

Karzai raised the issue of civilian casualties during NATO airstrikes, a major obstacle to promoting support for the coalition and government fight against militants. He said he told Gates that the bombing of Afghan homes must not be repeated.

"We can't take any more airstrikes where many civilians get killed. And we can't keep up our peace efforts when civilians get killed with those Taliban who are not connected to al Qaeda," Karzai said.

The four fatalities are the latest international troop deaths in Afghanistan, where killings have mounted monthly this year as fighting has intensified between insurgents and soldiers.

The Afghan NGO safety office told CNN that in the first quarter of this year, it tracked a 54 per cent rise in violence across the country, including incidents targeting NATO, the insurgency and civilians. It expected the trend to continue in the second quarter and that the violence seemed to be mostly rising in the eastern part of the country.

The troops, whose nationalities were not immediately released, died after the explosion struck their vehicle during a routine patrol, said Maj. Tim James, an ISAF spokesman. A fifth person, a civilian, was injured, he said.

In its claim of responsibility, the Taliban said the four were Americans and the incident took place in Kunar province.

They are the latest of 10 international troop deaths this month. In May, 58 coalition troops were killed, according to a CNN count of coalition figures, and more than 225 international soldiers have died in Afghanistan this year.

On Friday, two international troops were killed, including a British soldier in Helmand province. On Thursday, one German and one Polish soldier were killed in separate incidents, and a French soldier was killed on Wednesday.

Other violence erupted in Afghanistan.

In the southern city of Kandahar, a bomb placed on a motorbike killed the secretary of the local police chief while he was at the city's university, the local government said. A student was injured in the blast. The police chief's secretary was studying engineering at the university.

In the country's northeastern Panjshir province, an Italian anti-drug expert was killed during a private visit on Friday, military police told CNN.

Authorities have opened a case into the death of the man, Col. Cristiano Congiu, who worked at the Italian Embassy in Kabul since 2007.

Congiu was with an American woman when she was pushed violently against a wall by an Afghan man.

The Italian, setting out to defend the woman, shot and injured the Afghan, Italian police said.

Panjshir Police Chief Saboor Nasiry told CNN that the Italian was killed later when he was attacked by relatives of the injured man.

CNN's Nick Paton Walsh and Joe Sterling and Journalist Livia Borghese contributed to this report