New Delhi: Congress President Sonia Gandhi on Monday appealed to people to maintain peace in Jammu and Kashmir and said that the political gains made over the past two decades in the state must not get lost. "There can be no compromise on matters relating to national security. Terrorism must be dealt with firmly. Even so, the death of so many of our citizens and attack on security forces is very painful," said Sonia Gandhi. "The political process has made many gains in Jammu and Kashmir, particularly over the last two decades and these must not get lost. I appeal to my brothers and sisters in the valley to allow political parties to find durable and enduring ways of fulfilling their aspirations meaningfully in a peaceful and democratic manner," she added. Jammu and Kashmir has witnessed heightened tension following the killing of Hizbul commander Burhan Wani, a poster boy of militancy in the state last Friday. At least 22 people have been killed in clashes between protesters and security forces since the killing and curfew imposed in the valley.