In a stern message to Pakistan, the United States has asked it to shed its policy of using insurgents like LeT as a strategic tool and warned that if it cannot deliver against terrorists, the US may be impelled to use any means at its disposal.

The message, which has been conveyed in a letter from US President Barack Obama to his Pakistani counterpart Asif Ali Zardari, also includes an offer by him to try to reduce tensions between India and Pakistan, media reported here.